Advertisements
Advertisements
Question
Write scientific reason.
A coil made up of alloy Nichrome is used in the electric heater cooker as a resistor.
Advertisements
Solution
- The electric heater-cooker works on the principle of heating effect of electric current.
- Alloys (such as nichrome) as compared to metals have higher resistivity.
- Unlike metals they can be heated to higher temperature.
Hence, a coil made up of alloy nichrome is used in the electric heater-cooker as a resistor.
APPEARS IN
RELATED QUESTIONS
Compute the heat generated while transferring 96000 coulomb of charge in one hour through a potential difference of 50 V.
An electric heater of resistance 8 Ω draws 15 A from the service mains 2 hours. Calculate the rate at which heat is developed in the heater.
Write Joule's law of heating.
An electric kettle rated at 220 V, 2.2 kW, works for 3 hours. Find the energy consumed and the current drawn.
Why does the connecting cord of an electric heater not glow hot while the heating element does?
How much heat will an instrument of 12 W produce in one minute if it is connected to the heat produced by it?
The current passing through a room heater has been halved. What will happen to the heat produced by it?
Give a scientific reason:
For electric power transmission, copper or aluminium wire is used.
Name any six domestic appliances based on the heating effect of electric current.
Write the mathematical expression for Joule’s law of heating.
The ‘live’ and the ‘neutral’ wires have potential difference of _______.
Which of the following substance contracts on heating?
What is used to turn off the sudden increase in current in the electrical circuit of the house nowadays?
Right or wrong sentence.
Live wire and neutral wires have a 220 V potential difference.
When does overloading occur?
Explain the heating effect of electric current.
Heating effect of current is called ______
Which of the following is correct?
Mark the correct choice
- Assertion: Electric appliances with a metallic body have three wire connections.
- Reason: Three-pin connections reduce the heating of the connecting wires.
An electric iron draws a current of 4 A when connected to 220 V mains. Its resistance must be:
Assertion: Bending of wire decreases the resistance of the electric wire.
Reason: The resistance of a conductor depends on length, thickness, nature of material and temperature of the conductor.
(a) Observe the diagram given below and state whether the bulb will glow or not when we switch on K.

(b) Is it safe to handle the bulb when the switch is OFF?
(c) Give a reason for your answer in (b).
An electric component used as a safety device is electric circuit is ______.
What are the uses of electromagnets?
What is an electric fuse made up of?
What are the factors affecting heating effect of electric current?
It would cost a man Rs. 3.50 to buy 1.0 kW h of electrical energy from the Main Electricity Board. His generator has a maximum power of 2.0 kW. The generator produces energy at this maximum power for 3 hours. Calculate how much it would cost to buy the same amount of energy from the Main Electricity Board.
______ wire is used in the filament of the bulbs.
Fuse is a strip of alloy wire which is made up of lead and tin with a very low ______.
Match the following
| 1. | Bulb | a. | Conductor |
| 2. | Electroplating | b. |
Insulator |
| 3. | Pure water | c. | Heating effect of current |
| 4. | Salt solution | d. | Chemical effect of current |
Name the effect of the current responsible for the glow of the bulb in an electrical circuit.
A student boils water in an electric kettle for 20 minutes. Using the same mains supply he wants to reduce the boiling time of water. To do so should he increase or decrease the length of the heating element? Justify your answer.
An electrochemical cell converts ______ energy into ______ energy.
In which of the following applications of Iron, rusting will occur most? Support your answer with valid reason.
| A | B | C | D |
![]() |
![]() |
![]() |
![]() |
When a current I flows through a wire of resistance R for time t then the electrical energy produced is given by ______.
An electric iron of resistance 20 Ω draws a current of 5 A. The heat developed in the iron in 30 seconds is ______.




